Detectors are sometimes used in the field of analytical instruments for detecting chemical substances, including explosive substances and/or nuclear, biological and chemical warfare (NBC) agents.
Apparatuses for and methods of performing an analysis of a chemical substance, including an analysis utilizing ion mobility spectrometry (IMS), are known. Often, these apparatus/methods including parameters which enhance an amount of the chemical substance available for analysis, thus improving the macroscopic sensitivity of the analysis. An increased concentration of substance available for analysis, which can be deposited on a membrane of an ion mobility spectrometer (IMS) system, in turn, increases the macroscopic sensitivity of the analysis by allowing additional sample chemical to pass through the membrane of an IMS system for analysis, due to the additional amounts of sample transferred to the membrane.
Apparatuses for and methods of performing an analysis of a chemical substance often utilize particle separators to separate particles from a gas (such as air). Particles often are collected for analysis using inertial separators, such as cyclones. See, e.g., U.S. Pat. No. 6,508,864. Generally, inertial separators operate by using a combination of forces, such as centrifugal, gravitational, and inertial, to separate particles from the gas in which they are contained. For cyclones, particles generally are separated using centripetal force. Specifically, cyclonic motion causes the particles to separate from the gas and impact a wall of the cyclone that can be wetted with a liquid, such as a suspension buffer. The particles are then removed from the cyclone in a fluid-particle mixture. The particles can exit through an outlet in the chamber and into a conduit extending from the outlet.
Because inertial separators use relatively small volumes of fluid and small diameter fluid conduits (e.g. tubing or other sample collection means), inertial separators, including cyclones, can be prone to blockages. The blockages can be caused by large particles lodged in a conduit or smaller particles aggregating to cause a blockage in a conduit.
Blockages can be removed or prevented by several means. For example, some inertial separators use filters to prevent particles from entering the fluid conduits. Filters capture the particles that are of interest, however, so they cannot simply be excluded, because such exclusion could interfere with the function of the inertial separator. Syringes also can be used to manually remove blockages. For example, an operator uses a syringe to manually inject an amount of fluid into the conduit closest to the chamber of the inertial separator. The fluid dislodges any particles blocking the outlet of the conduit. The dislodged particles can be flushed back out through the sample conduit and dispersed in a larger volume of fluid retained in the inertial separator. Eventually, the particles exit the inertial separator through the outlet and into an analysis device. These methods of preventing and clearing blockages suffer from several limitations. Specifically, filters can hinder the efficient collection of particles. Syringes require an operator to attend to the device and remove blockages when they occur. This is problematic, because inertial separators are often left running unattended for prolonged periods. Thus, blockages go undetected and unresolved because manual injection systems require an operator to detect a blockage and to initiate a blockage clearance procedure.